1. Field of the Invention
The present invention generally relates to image reading apparatuses, and more particularly, to an image reading apparatus having a processing portion and an optical system detachably provided thereto.
2. Description of the Related Arts
Office automation equipment of recent years have been developing from a stand-alone type to a multifunctional type. Among those multifunctional equipment, image reading apparatuses have become important as input means in preparing an original of an image or documents.
The image reading apparatuses analyze an original image into a minute net pattern, convert image portions and non-image portions into binary of black and white, respectively, and output the converted results to an external equipment as a digital signal. As such image reading means, apparatuses of handy scanner type which are superior in portability add have applicability to a wide range of objects to be read have been developed, as well as those of an installed type.
An image reading apparatus is generally comprised of an optical system which scans an original image to form an image and a processing portion which reads out the thus formed image and processes the read-out image.
The conventional image reading apparatus as described above has its optical system and processing portion integrally incorporated therein. Accordingly, it is impossible, for example, to enlarge the read width or change the reading manner in reading out from one original.
Further, though a handy scanner whose optical system comprises CCD and which can be separated from its processing portion has been developed, the optical system and the CCD are still manufactured as an integral part. Therefore, the read width can not be easily changed.
As described above, in order to change the read width and the like, an additional image reading apparatus becomes necessary, resulting in a disadvantage in terms of cost and also of use.